LibC: Add sys/auxv.h with getauxval

userspace/libraries/LibC/CMakeLists.txt

@@ -40,6 +40,7 @@ set(LIBC_SOURCES
 	stdlib.cpp
 	string.cpp
 	strings.cpp
+	sys/auxv.cpp
 	sys/banan-os.cpp
 	sys/epoll.cpp
 	sys/eventfd.cpp

userspace/libraries/LibC/include/elf.h

@@ -149,6 +149,18 @@ __BEGIN_DECLS
 #define DT_LOPROC       0x70000000
 #define DT_HIPROC       0x7FFFFFFF
 
+#define AT_NULL        0
+#define AT_IGNORE      1
+#define AT_EXECFD      2
+#define AT_PHDR        3
+#define AT_PHENT       4
+#define AT_PHNUM       5
+#define AT_PAGESZ      6
+#define AT_BASE        7
+#define AT_SHARED_PAGE 0xFFFF0001
+#define AT_STACK_BASE  0xFFFF0002
+#define AT_STACK_SIZE  0xFFFF0003
+
 #define R_386_NONE          0
 #define R_386_32            1
 #define R_386_PC32          2

userspace/libraries/LibC/include/sys/auxv.h

@@ -0,0 +1,14 @@
+#ifndef _SYS_AUXV_H
+#define _SYS_AUXV_H 1
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#include <elf.h>
+
+unsigned long getauxval(unsigned long type);
+
+__END_DECLS
+
+#endif

userspace/libraries/LibC/sys/auxv.cpp

@@ -0,0 +1,40 @@
+#include <sys/auxv.h>
+#include <unistd.h>
+
+#include <kernel/API/SharedPage.h>
+
+struct auxv
+{
+	unsigned long a_type;
+	unsigned long a_val;
+};
+
+static const auxv* s_auxv = nullptr;
+
+volatile Kernel::API::SharedPage* g_shared_page = nullptr;
+
+__attribute__((constructor(101)))
+static void _init_auxv()
+{
+	if (environ == nullptr)
+		return;
+
+	const char* const* null_env = environ;
+	while (*null_env)
+		null_env++;
+
+	s_auxv = reinterpret_cast<const auxv*>(null_env + 1);
+
+	if (auto value = getauxval(AT_SHARED_PAGE))
+		g_shared_page = reinterpret_cast<volatile Kernel::API::SharedPage*>(value);
+}
+
+unsigned long getauxval(unsigned long type)
+{
+	if (s_auxv == nullptr)
+		return 0;
+	for (const auxv* aux = s_auxv; aux->a_type != AT_NULL; aux++)
+		if (aux->a_type == type)
+			return aux->a_val;
+	return 0;
+}

userspace/libraries/LibC/unistd.cpp

@@ -2,12 +2,6 @@
 #include <BAN/Debug.h>
 #include <BAN/StringView.h>
 
-#include <LibELF/AuxiliaryVector.h>
-
-#include <kernel/API/SharedPage.h>
-#include <kernel/API/Syscall.h>
-#include <kernel/Memory/Types.h>
-
 #include <ctype.h>
 #include <dlfcn.h>
 #include <errno.h>
@@ -19,6 +13,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/auxv.h>
 #include <sys/banan-os.h>
 #include <sys/ioctl.h>
 #include <sys/stat.h>
@@ -36,7 +31,6 @@ struct init_funcs_t
 
 extern "C" char** environ;
 
-volatile Kernel::API::SharedPage* g_shared_page = nullptr;
 
 #define DUMP_BACKTRACE 1
 #define DEMANGLE_BACKTRACE 0
@@ -58,28 +52,11 @@ void __stack_chk_fail(void) { abort(); }
 
 static void __dump_backtrace(int, siginfo_t*, void*);
 
-static LibELF::AuxiliaryVector* find_auxv(char** envp)
-{
-	if (envp == nullptr)
-		return nullptr;
-
-	char** null_env = envp;
-	while (*null_env)
-		null_env++;
-
-	return reinterpret_cast<LibELF::AuxiliaryVector*>(null_env + 1);
-}
-
 extern "C" void _init_libc(char** environ, init_funcs_t init_funcs, init_funcs_t fini_funcs)
 {
 	if (::environ == nullptr)
 		::environ = environ;
 
-	if (auto* auxv = find_auxv(environ))
-		for (auto* aux = auxv; aux->a_type != LibELF::AT_NULL; aux++)
-			if (aux->a_type == LibELF::AT_SHARED_PAGE)
-				g_shared_page = static_cast<Kernel::API::SharedPage*>(aux->a_un.a_ptr);
-
 #if defined(__x86_64__)
 	if (uthread* self = reinterpret_cast<uthread*>(syscall(SYS_GET_FSBASE)))
 #elif defined(__i686__)

userspace/libraries/LibELF/include/LibELF/AuxiliaryVector.h

@@ -27,6 +27,8 @@ namespace LibELF
 		AT_BASE   = 7,
 
 		AT_SHARED_PAGE = 0xFFFF0001,
+		AT_STACK_BASE  = 0xFFFF0002,
+		AT_STACK_SIZE  = 0xFFFF0003,
 	};
 
 }